Method of tunnel boring and tunnel reinforcement mats

ABSTRACT

Reinforcements mats for tunnel boring are prepared in the form of grid structures of crossing reinforcement rods and additional reinforcing profile members, typically angles with their apices facing transverse to the tunnel axis and welded to the reinforcement rods; the mats are shaped to fix approximately the tunnel outlined and located adjacent each other as the tunnel boring machine bores the tunnel; concrete is then sprayed against the mats, between the tunnel walls and the mats and covering the mats. To join the mats together, terminal ends of reinforcement rods are left free to slide against and adjacent rods of a preceding mat; the angles may be located to slide within each other.

Bernold States Patent 1 Jan. 7, 1975 [76] Inventor: Jean Bernold, Hasenberg,

Walenstadt, Switzerland 22 Filed: Sept. 26, 1972 21 Appl. No.: 293,850

[30] Foreign Application Priority Data Sept. 29, 1971 Switzerland 14124/71 [52] US. Cl 61/45 R, 52/741, 61/63 [51] hit. C1 ..E21d 11/10 [58] Field of Search 61/45 R, 42, 63, 84, 85; 52/741, 664, 665, 669

[56] References Cited UNITED STATES PATENTS 495,036 4/1893 Hegbom 52/669 X 1,023,526 4/1912 Oliver 52/669 X 1,474,808 11/1923 Zucco 61/45 R X 1,534,968 4/1925 Larson 52/669 1,876,205 9/1932 Crom 61/45 R X 2,187,223 1/1940 Cory 52/741 X 3,300,938 1/1967 Van Schyndel et a1 52/664 3,381,479 5/1968 CurZio 61/45 R 3,389,560 6/1968 Zemsky 61/45 RX 3,638,434 2/1972 Delaere 61/45 R 3,712,825 1/1973 Yocum 52/741 X FOREIGN PATENTS OR APPLICATIONS 1,197,728 7/1970 Great Britain 52/741 Primary Examiner-Dennis L. Taylor Attorney, Agent, or Firm-Flynn & Frishauf [5 7] ABSTRACT Reinforcements mats for tunnel boring are prepared in the form of grid structures of crossing reinforcement rods and additional reinforcing profile members, typically angles with their apices facing transverse to the tunnel axis and welded to the reinforcement rods; the mats are shaped to fix approximately the tunnel outlined and located adjacent each other as the tunnel boring machine bores the tunnel; concrete is then sprayed against the mats, between the tunnel walls and the mats and covering the mats. To join the mats together, terminal ends of reinforcement rods are left free to slide against and adjacent rods of a preceding mat; the angles may be located to slide within each other.

10 Claims, 4 Drawing Figures METHOD OF TUNNEL BORING AND TUNNEL REINFORCEMENT MATS CROSS REFERENCE TO RELATED APPLICATION U.S. Ser. No. 262,874, Bernold, filed June 14, 1972, now abandoned.

The present invention relates to tunnel boring, and more particularly to a method, and structure to cover the tunnel walls as a tunnel is being bored by a boring machine.

As tunnels are driven, it is known to block the shaft, in order to insure safety and prevent rock falls or the like. It has been proposed to use steel mats made of structural steel and to secure the mats in the tunnel walls by means of anchors, driven pins or the like, and further to place reinforcement arches ever so often, for example every three to four feet or so. The reinforcement arches are made of appropriately strong material of heavy cross section. Thereafter, concrete is sprayed on the steel mat. The concrete layer may, however, have only a small thickness since the mats of structural steel, that is, the reinforcement mats are directly applied against the wall of the tunnel as it has been bored. Usually, the reinforcement mats are made of gridshape, crossing round rods or bars which have only relatively small stiffness so that they do not substantially reinforce the tunnel wall against static pressure without being covered by concrete. The relatively thick and strong reinforcing arches, placed at intervals, have the disadvantage that they interrupt the layer of sprayed concrete so that they are a source of cracks. They also decrease the overall useful diameter of the tunnel sufficiently to interfere with free movement of a tunnel boring machine, and retraction of the tunnel boring machine through the previously placed reinforcement arches.

It is an object of the present invention to improve tunnel boring and, more specifically, to provide a method and devices useful in the method which can simply be applied, just behind the cutter heads of the tool bore machines and still permit efficient reinforcements of the tunnel without substantially decreasing the diameter of the tunnel being bored. Further, the

. method and the device should permit ready application of sprayed concrete.

Briefly, reinforcement mats are shaped at the approximate outline of the tunnel being bored, and the shaped reinforcement mats are located adjacent each other as the tunnel boring machine proceeds. Thereafter, the concrete is sprayed against the mats, between the mats, and the tunnel wall. The reinforcement mats are rein forced in the circumferential direction to accept surrounding pressure of the earth through which the tunnel is being bored. Adjacent mats are interconnected.

The mats, in accordance with an embodiment of the invention, preferably include grid-shaped structures which have reinforcements in the form of profile shapes, preferably angle irons having their apices directed transverse to the tunnel axis and welded to crossing reinforcement rods. The terminal ends of the reinforcement rods extending transverse to the reinforcing angles are left free so that the mats can be slid against each other, axially or transversely with respect to the tunnel, and adjacent angles snapped or slid into each other to provide for overlap of the mats and thus for a complete structural unity permitting easy splicing together of the mats and secure holding of surrounding rocks or other structure for subsequent application by sprayed concrete.

The invention will be described by way of example with reference to the accompanying drawings, wherein:

FIG. 1 is a top view of a reinforced tunnel wall mat;

FIG. 2 is a fragmentary enlarged cross section of a tunnel wall mat located adjacent the side of a tunnel wall and having sprayed concrete applied thereto;

FIG. 3 is a fragmentary cross section, in circumferential direction with respect to the tunnel, illustrating an intermediate position of ends of a pair of mats being slid against each other; and

FIG. 4 is a cross sectional view along line lVlV of FIG. 3.

Separate mat structures 1 are interconnected along the circumference of the tunnel, as the tunnel is driven forward by a boring machine. Each time, when the boring machine has progressed by a predetermined distance, corresponding roughly to the length of a mat, mats can be joined together. The mats are customary reinforcement-type mats 2 formed of round rods 3, 4, crossing each other in grid-like manner. A plurality of angle irons 5 are secured to the mats on one side. The two legs 6, 7 (FIG. 4) of the angle irons face outwardly, so that the apex 8 of any angle iron can be connected with the mats 2, preferably by welding, to provide a secure interconnection. Before being secured together, the mats are fitted approximately to the radius, or outlined shape of the tunnel wall, or portions thereof, so that the angle irons 5 are on the outside of the mats and, as seen in FIG. 2, fit approximately against the tunnel wall 9. Thus, the angles not only contribute to stiffening and reinforcing the mats, but additionally provides for spacers from the rock or other wall, so that a greater thickness of concrete 10 can be sprayed against the mats and to surround the reinforcing rods. Securing the angle iron 5 along its apex 8 to mat 2 has the advantage that the leg 6, 7 facing the tunnel wall reduce splashing and back-splash and spray of the cement as it is being sprayed against the tunnel wall. The thickness of the cement layer can further be increased by utilizing the known wet spray method, using a lower spraying pressure.

The mat 2 is thus additionally reinforced by the angle iron 5 so that the mat will have a sufficient stiffness to provide a preliminary holding structure to be placed immediately behind the cutter heads as the cutter heads proceed into the rock.

The mats 1 can be connected in circumferential direction of the tunnel by overlapping their ends, as best seen in FIGS. 3 and 4. The rods 11 and 12, or 13 and 14, and extending longitudinally of the tunnel axis and adjacent the ends of the mats are so welded to the angle 5 so that the edges, or ends of two mats, as seen in FIG. 3, can be pushed against each other in the direction of arrow 15. Mat 2 is lifted at its edge off the angle 5 and pushed adjacent the other mats until it meets the first rod 16 welded to an angle 5. The angles will then interengage (see FIG. 4) and slide against each other. Thereafter, the overlapping portions of a pair of adjacent mats can be secured together for example by means of tie wires 17, clamps, connecting bolts, pins, welding in place, or any other suitable interconnection method.

The distance between the angles 5 on the reinforcement mat 2 has to be matched to the pressure of the mountain, or rock through which the tunnel is being bored. In any event, the overall mat, as reinforced, is still sufficiently light and ready to handle, so that separate reinforcing arches to secure the tunnel wall will no longer be necessary. Utilizing a sufficient number of angle iron provides high reinforcing strength for the concrete layer subsequently applied thereof.

The angles 5 provide a free clear space in the direction to the tunnel wall, which may be utilized as a connecting space to collect and draw off water. Before the concrete is sprayed against the mats, drainage tubes 18 of perforated plastic material, or the like, may be placed in the angle included by the angle irons see FIG. 2 which will then fit against the wall of the rock. The water thus collected can be connected from the tubes 18 to a common sump line close to the floor of the tunnel.

Mounting of the mats just behind the tunnel boring head can be facilitated by movable accessories or do]- lies which guide the mats and hold them against the tunnel walls and press them thereagainst before they are connected to the tunnel wall if necessary by means of bolts, anchors or the like. The mats need not, however, be secured to the tunnel wall if they are placed over the circumference of the tunnel and bear on the tunnel floor, or if they are placed entirely around the tunnel since, in such types of tunnels, the mats are sufficiently held together by their interconnection between themselves.

Various changes and modifications may be made within the scope of the inventive concept.

A schematic illustration of a spraying arrangement which, by in itself is known, is shown in the cross reference application Ser. No. 262,874.

For boring tunnels, for example in the Alps, spacing of angles of about-68 cm has been found useful; the angles themselves may be ordinary 2.5 cm angles, of structural steel, that is, angles whose legs are about 2% cm long.

I claim: 1. In the art of tunnel boring utilizing a tunnel boring machine, the method of securing the tunnel walls comprising providing reinforced tunnel wall mats having gridlike interconnected rods and reinforcing angle irons the rods extending in one direction and the angle irons transverse thereto and being secured to the angle irons at the apices thereof, and wherein the terminal ends of the angle irons (5) are left free from crossing rods and the other rods extend to the vicinity of the terminal ends of the angle irons;

shaping the reinforced mats in the approximate shape of the tunnel walls over at least a portion of the walls bored by the boring machine and immediately following said boring machine;

locating a shaped, reinforced mat against the tunnel walls with the apex of the angle extending transversely of the axis of the tunnel and facing inwardly of the tunnel, the open angle of the angle irons facing the tunnel walls to space the grid-like rods from the tunnel wall;

sliding the next mat in parallel to the mat located against the tunnel walls;

interfitting the next adjacent angle members of the thus adjacently located mats by interengaging a terminal angle iron free from rods of one mat with an angle iron of the adjacently located mat;

and spraying concrete against the mats, between the mats and the tunnel wall, the open angles of the angle members forming a back splash shield.

2. Method according to claim 1 further comprising locating the rods longitudinally and circumferentially of the tunnels to extend in two transverse direction;

and interconnecting adjacent terminal ends of the reinforcing mats and of the reinforcing rods then following with the spraying step by spraying the interconnected portions.

3. Method according to claim 1 further comprising fitting the first angle iron of a mat into the last angle iron of a preceding mat so that the angle irons will fit into each others;

interconnecting adjacent mats;

and then finishing with the spraying step and spraying the interconnected portions of the mats.

4. Method according to claim 3 including the step of engaging the terminal ends of rods of thus adjacently located, interfitted mats.

5. Method according to claim 3 including the step of tying together the interfitting angle irons and the rod.

6. Tunnel reinforcement structure to reinforce tunnel walls being bored by a tunnel boring machine comprismg a plurality. of angle irons (5) having terminal end portions the angle irons being shaped and bent to approximately fit the tunnel wall about at least a portion thereof and adapted to be located transversely to the tunnel axis;

a plurality of longitudinal reinforcement rods (ll, 12) relatively located in grid-shape pattern, the angle irons (5) being located with their apices transverse to, and towards the tunnel axis, the apices of the angle irons being welded to the longitudinal reinforcement rods at crossing points of the angles and rods;

and wherein the terminal ends of the angle irons are left free from crossing rods and the other rods extend to the vicinity of the terminal ends of the angle irons to permit interfitting of an angle iron of a next adjacent mat with the end of the angle member free from the rods to thereby permit interconnection of adjacent mats by an interengaging, interlocking fit of angle irons fitting within each other.

7. Reinforcement structure according to claim 6 wherein the angle irons are spaced from each other by approximately in the order of from 6 to 8 cm and are formed of approximately 2% cm angles.

8. Reinforcement structure according to claim 6 wherein the reinforcement rods are crossing at approximately right angular directions and are of essentially circular cross section.

9. Reinforcement structure according to claim 6 wherein the angle irons are located at the convex side of the mat adapted to face the tunnel wall.

10. Tunnel reinforcement structure assembly comprising a plurality of tunnel reinforcement mat structures according to claim 6, wherein the free terminal ends of the angle irons of one structure are fitted into the angle irons of a next adjacent structure, the rod (16) first welded to the free terminal ends of the angle irons forming a stop for the angle irons of the next adja- CCI'II mat structure. 

1. In the art of tunnel boring utilizing a tunnel boring machine, the method of securing the tunnel walls comprising providing reinforced tunnel wall mats having grid-like interconnected rods and reinforcing angle irons the rods extending in one direction and the angle irons transverse thereto and being secured to the angle irons at the apices thereof, and wherein the terminal ends of the angle irons (5) are left free from crossing rods and the other rods extend to the vicinity of the terminal ends of the angle irons; shaping the reinforced mats in the approximate shape of the tunnel walls over at least a portion of the walls bored by the boring machine and immediately following said boring machine; locating a shaped, reinforced mat against the tunnel walls with the apex of the angle extending transversely of the axis of the tunnel and facing inwardly of the tunnel, the open angle of the angle irons facing the tunnel walls to space the grid-like rods from the tunnel wall; sliding the next mat in parallel to the mat located against the tunnel walls; interfitting the next adjacent angle members of the thus adjacently located mats by interengaging a terminal angle iron free from rods of one mat with an angle iron of the adjacently located mat; and spraying concrete against the mats, between the mats and the tunnel wall, the open angles of the angle members forming a back splash shield.
 2. Method according to claim 1 further comprising locating the rods longitudinally and circumferentially of the tunnels to extend in two transverse direction; and interconnecting adjacent terminal ends of the reinforcing mats and of the reinforcing rods then followinG with the spraying step by spraying the interconnected portions.
 3. Method according to claim 1 further comprising fitting the first angle iron of a mat into the last angle iron of a preceding mat so that the angle irons will fit into each others; interconnecting adjacent mats; and then finishing with the spraying step and spraying the interconnected portions of the mats.
 4. Method according to claim 3 including the step of engaging the terminal ends of rods of thus adjacently located, interfitted mats.
 5. Method according to claim 3 including the step of tying together the interfitting angle irons and the rod.
 6. Tunnel reinforcement structure to reinforce tunnel walls being bored by a tunnel boring machine comprising a plurality of angle irons (5) having terminal end portions the angle irons being shaped and bent to approximately fit the tunnel wall about at least a portion thereof and adapted to be located transversely to the tunnel axis; a plurality of longitudinal reinforcement rods (11, 12) relatively located in grid-shape pattern, the angle irons (5) being located with their apices transverse to, and towards the tunnel axis, the apices of the angle irons being welded to the longitudinal reinforcement rods at crossing points of the angles and rods; and wherein the terminal ends of the angle irons are left free from crossing rods and the other rods extend to the vicinity of the terminal ends of the angle irons to permit interfitting of an angle iron of a next adjacent mat with the end of the angle member free from the rods to thereby permit interconnection of adjacent mats by an interengaging, interlocking fit of angle irons fitting within each other.
 7. Reinforcement structure according to claim 6 wherein the angle irons are spaced from each other by approximately in the order of from 6 to 8 cm and are formed of approximately 2 1/2 cm angles.
 8. Reinforcement structure according to claim 6 wherein the reinforcement rods are crossing at approximately right angular directions and are of essentially circular cross section.
 9. Reinforcement structure according to claim 6 wherein the angle irons are located at the convex side of the mat adapted to face the tunnel wall.
 10. Tunnel reinforcement structure assembly comprising a plurality of tunnel reinforcement mat structures according to claim 6, wherein the free terminal ends of the angle irons of one structure are fitted into the angle irons of a next adjacent structure, the rod (16) first welded to the free terminal ends of the angle irons forming a stop for the angle irons of the next adjacent mat structure. 